There is a growing need to develop non-viral based carriers for the delivery of drugs, plasmic DNA, shRNA, and the like for pharmaceutical and therapeutic applications. Cationic lipid based liposomal carriers are an attractive non-viral delivery modality. Advantages of liposomal vectors include safety, lack of immunogenicity, ability to package large DNA molecules, and ease of preparation. For example, cationic lipid/DNA complexes may be used for in vitro and in vivo gene delivery. These lipid-gene complexes may thus be used in various gene therapy applications.
The size of the cationic and DNA complexes, which are referred to herein as “lipoplexes,” dictates the efficiency of gene transfection. Conventionally, lipoplex formation was accomplished by hand shaking or vortexing a mixture of cationic lipids and DNA. Unfortunately, these conventional techniques to generate lipoplexes have largely produced lipoplexes having characteristics that are irreproducible. In addition, conventional preparation processes such as hand shaking and vortexing suffer from the problem that the resulting lipoplexes have a large size distribution. Because the size of the individual lipoplex particles affects the rate of transfection, a population of lipoplexes having a broad array of sizes will adversely affect the overall efficiency of gene transfection.
Various parameters are known to affect the lipoplex sizes which include, the order of mixing of the cationic liquid and the DNA, the rate of mixing, and the mixture incubation time. The lack of control over the biophysical parameters that affect lipoplex generation is thus a barrier to consistently obtaining stable and monodisperse lipoplex formulations. There thus is a need for a methods and devices that are able to efficiently formulate monodisperse lipoplex assemblies. The device and method should be able to rapidly produce monodisperse lipoplex assemblies in a narrow size distribution. Moreover, there is a further desire and need to reduce the size of the lipoplex assemblies that are generated. By reducing the size of the lipoplex assemblies generated, this will generally reduce the amount of incubation time needed to form the complete assemblies since the incubation time is generally proportional to the size of the lipoplexes due to aggregation. Moreover, there is a need for a microfluidic-based device that can integrate multiple processing steps such as mixing and incubation into a relatively small device.